The interest in using non-wood materials, such as trichomes and bamboo fibers, to make fibrous structures, for example sanitary tissue products, has recently increased in light of the continuing efforts relating to sustainability.
One non-wood material that shows promise as a replacement or partial replacement of wood pulp fibers in fibrous structures, such as sanitary tissue products, is trichomes; namely, individualized trichome fibers obtained from plants, such as Stachys byzantina plants, for example Lamb's Ear plants. However, “clean” individualized trichome fibers are challenging to obtain in large amounts due to the impurities, such as stems, specks, dirt, clay, sand, and other non-trichome materials that are present with the individualized trichome fibers as a result of the processes for harvesting and extracting the individualized trichome fibers from the plants. These impurities find their way into fibrous structures made with the individualized trichome fibers and result in the fibrous structures looking dirty and filled with specks that render the fibrous structures unacceptable to consumers of the fibrous structures.
Known processes for individualizing (separating) trichome fibers from plants typically utilize mechanical cutting and air sorting operations. Such operations are very costly, require high amounts of maintenance, are normally batch processes rather than continuous processes, and the individualized trichome fibers still contain a level of non-trichome materials, for example specks, sand, stems, that is not consumer acceptable.
Processes for isolating trichome fibers from trichome sources are known in the art. For example, mechanical processes for isolating (individualizing) trichome fibers from trichome sources to obtain individualized trichome fibers are known. However, such mechanical processes result in the individualized trichome fibers containing undesirable contaminants, such as dirt, fines, and non-trichome materials, such as parts of leaves and/or stems.
In addition, known benchtop scale chemical separation processes for removing trichomes, for example Arabidopsis trichomes from the Brassicaceae family, from trichome sources are known. Such a known benchtop scale chemical separation process utilizes a mixture of a chelating agent, such as ethylene glycol bis-(β-aminoethyle ether)-N,N,N′,N′-tetraacetic acid (“EGTA”) and a nonionic surfactant, such as Triton X-100. The process incubates the trichome source in a mixture of EGTA and Triton X-100 at 4° C. for 16-24 hours and/or at 50° C. for 1 hour followed by gentle rubbing using an artist's paintbrush. Such as process is not commercially feasible on a large scale commercial process. Nor are the Arabidopsis trichomes considered trichome fibers in accordance with the present invention in light of their thorny structure as shown in Prior Art FIG. 1. Such a thorny trichome would not be suitable for use in sanitary tissue products, such as bath/toilet tissue, unlike the non-thorny trichome fibers, especially the trichome fibers from the Labiatae family.
One problem with known processes for individualizing trichome fibers from trichome sources (for example plants) is the inability to remove non-trichome materials (impurities present in the plants and/or growing environments from which the plants are harvested) cost effectively and/or in a continuous process such that the individualized trichomes contain no or a consumer acceptable level of non-trichome materials so that the individualized trichome fibers may ultimately be used to make consumer desirable fibrous structures for sanitary tissue products. Further, known processes result in contaminated individualized trichome fibers and/or low yields and/or are not commercially feasible on a large scale, for example using an artist's paintbrush to rub the trichome source to cause the trichomes to separate from the trichome source is not a cost-effective, commercially viable step in a process for removing trichomes from a trichome source.
Accordingly, there is a need for a process that is able to individualize trichome fibers from trichome sources (for example plants) in a cost effective, low maintenance, continuous process that results in the individualized trichome fibers having no or a consumer acceptable level of non-trichome materials (impurities present in the plants and/or growing environments from which the plants are harvested) such that the individualized trichome fibers can be used to make consumer desirable fibrous structures, such as sanitary tissue products.